https://github.com/pjfanning/jackson-scala3-reflection-extensions
Jackson scala3 support that uses gzoller/scala-reflection to get type info
https://github.com/pjfanning/jackson-scala3-reflection-extensions
jackson jackson-module scala3
Last synced: 24 days ago
JSON representation
Jackson scala3 support that uses gzoller/scala-reflection to get type info
- Host: GitHub
- URL: https://github.com/pjfanning/jackson-scala3-reflection-extensions
- Owner: pjfanning
- License: apache-2.0
- Created: 2021-11-04T23:34:23.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2025-04-04T17:54:46.000Z (about 1 month ago)
- Last Synced: 2025-04-11T03:52:55.979Z (24 days ago)
- Topics: jackson, jackson-module, scala3
- Language: Scala
- Homepage:
- Size: 127 KB
- Stars: 4
- Watchers: 3
- Forks: 1
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
[](https://maven-badges.herokuapp.com/maven-central/com.github.pjfanning/jackson-scala3-reflection-extensions_3)
# jackson-scala3-reflection-extensions
Jackson Scala 3 support that uses [scala3-reflection](https://github.com/pjfanning/scala3-reflection)
to get type info based on Scala 3 [Tasty](https://docs.scala-lang.org/scala3/guides/tasty-overview.html) files
(or at compile time, see Performance section).
The problem that this lib solves in described in this [FAQ entry](https://github.com/FasterXML/jackson-module-scala/wiki/FAQ#deserializing-optionint-seqint-and-other-primitive-challenges).
The lib can also auto-discover subtypes if you are using Jackson's polymorphism support ([@JsonTypeInfo annotation](https://www.baeldung.com/jackson-inheritance#2-per-class-annotations)). You can omit the `@JsonSubTypes` if you dealing with sealed traits.
See [jackson-scala-reflect-extensions](https://github.com/pjfanning/jackson-scala-reflect-extensions) for the Scala 2 equivalent.
This lib is designed to used with [jackson-module-scala](https://github.com/FasterXML/jackson-module-scala). By default,
jackson-module-scala uses Java reflection to work out the class structure.
`ScalaReflectionExtensions` can be mixed into your ObjectMapper in as a similar way to jackson-module-scala's
[ClassTagExtensions](https://github.com/FasterXML/jackson-module-scala/blob/2.15/src/main/scala/com/fasterxml/jackson/module/scala/ClassTagExtensions.scala)
and [ScalaObjectMapper](https://github.com/FasterXML/jackson-module-scala/blob/2.15/src/main/scala-2.%2B/com/fasterxml/jackson/module/scala/ScalaObjectMapper.scala).
```scala
libraryDependencies += "com.github.pjfanning" %% "jackson-scala3-reflection-extensions" % "2.16.0"
```
```scala
import com.fasterxml.jackson.databind.json.JsonMapper
import com.fasterxml.jackson.module.scala.DefaultScalaModule
import com.github.pjfanning.jackson.reflection.ScalaReflectionExtensions
val mapperBuilder = JsonMapper.builder()
.addModule(DefaultScalaModule)
val mapper = mapperBuilder.build() :: ScalaReflectionExtensions
// this should also work but Jackson is moving to supporting only creating mapper instances from a builder
val mapper2 = new ObjectMapper with ScalaReflectionExtensions
mapper2.registerModule(DefaultScalaModule)
val instance = mapper.readValue[MyClass](jsonText)
```
## Performance
The code to calculate the class details can be slow, as detailed in [gzoller/scala-reflection](https://github.com/gzoller/scala-reflection).
The results are cached, so they won't be recalculated every time you call `readValue`.
If performance worries you then you should consider enabling the compiler plugin.
```scala
addCompilerPlugin("com.github.pjfanning" %% "scala3-reflection")
```